Machine for moulding under pressure metal connecting members of rotors of electric motors

ABSTRACT

The invention provides a machine for moulding under pressure short-circuiting bars and rings of rotors of electric motors formed initially from a stack of magnetic sheets formed with connecting apertures, the machine having a rotatable carrier member fitted with two diametrically opposed sleeves each adapted to receive a stack of sheets, rotation of the carrier member repeatedly through 180* presenting one sleeve to a feed hopper for the stacks and the other to a pair of opposed moulding dies which, when pressed against the end faces of the sleeve, form with the sleeve a complete mould into which is injected under pressure liquid metal which passes into and through the connecting apertures in the stack and into recesses in the dies to form rings on the end faces of the stack continuing from the apertures to form with the stack an assembled rotor which is then removed from the sleeve.

United States Patent MACHINE FOR MOULDING UNDER PRESSURE METALCONNECTING MEMBERS OF ROTORS OF ELECTRIC MOTORS 13 Claims, 24 DrawingFigs.

US. Cl 164/303, 164/109,164/333,18/20 H Int. Cl 822d 19/00, B22d 17/24Field of Search 164/98,

108, 109,111,113, 303, 332334, DIG. 10; 18/30 PM, 30 PR, 30 UM, 20 I, 20S 3,315,315 4/1967 Triulzi References Cited UNITED STATES PATENTSABSTRACT: The invention provides a machine for moulding under pressureshort-circuiting bars and rings of rotors of electric motors formedinitially from a stack of magnetic sheets formed with connectingapertures, the machine having a rotatable carrier member fitted with twodiametrically opposed sleeves each adapted to receive a stack of sheets,rotation of the carrier member repeatedly through 180 presenting onesleeve to a feed hopper for the stacks and the other to a pair ofopposed moulding dies which, when pressed against the end faces of thesleeve, form with the sleeve a complete mould into which is injectedunder pressure liquid metal which passes into and through the connectingapertures in the stack and into recesses in the dies to form rings onthe end faces of the stack continuing from the apertures to form withthe stack an assembled rotor which is then removed from the sleeve.

PATENTED SEP28l97l 3,608,622

FIG.1

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' snm a or 9 HG. 22 1s MACHINE FOR MOULDING UNDER PRESSURE METALCONNECTING MEMBERS OF ROTORS OF ELECTRIC MOTORS The present inventionrelates to a pressure-casting machine particularly, although notexclusively, for use in making rotors for squirrel cage electric motors.

In a manner known in itself, the production of parts of the above typeis carried out'in the following manner;

In a first step magnetic sheets having notches are stacked on atemporary spindle in a number determined according to the desired heightof the rotor, the stacking being effected in such a manner that thenotches formed in the sheets form inner tunnels leading to each lateralface of the rotor.

In a second step the stack of sheets thus formed is placed manually in aconventional pressure-casting machine, following which, by injection ofmolten metal, there is formed on the lateral faces short circuitingrings possibly having cooling fins, these rings are connected togetherby bars formed in the tunnels. In subsequent steps, the rotor and sprueswhich are attached thereto are extracted from the machine, againmanually.

The rotor thus obtained is then placed in a press arranged on the onehand to effect the cutting off of the above-mentioned sprues and on theother hand to ensure the extraction of the temporary spindle.

The manufacturing technique has disadvantages which are: slowproduction, particularly due to various handling operations; the use oftwo machines, respectively a pressure-casting machine and an auxiliarycutting press; inefficient use of the pressure-casting machine due totime wastage; the impossibility of forming a feed head on the lower partof the rotor which often leads to a defective quality of he cast metal;and finally the necessity to create a mold for each kind of rotor.

The present invention has for an object to eliminate these disadvantagesand to this end provides a machine of simple and robust constructionhaving numerous advantages compared with the manufacturing techniquesknown hitherto.

According to the invention, a machine for casting under pressure metalconnecting members of rotors of electric motors formed initially from astack of magnetic sheets having connecting apertures, said machinecomprising a rotatable carrier member adapted to embrace at least twosleeves each adapted to receive in succession a stack of sheets, meansfor intermittently rotating said carrier member through a given angle tocarry each of said sleeves in succession firstly to a combined feed anddelivery station at which a stack of sheets is inserted into the sleeve,then to a casting station where the sleeve is positioned between a pairof opposed molds formed with casting recesses shaped to correspond withthe arrangement of the connecting apertures in the end faces of thestack of sheets, means at the casting station for pressing the pair ofmolds respectively into engagement with the end faces of the sleeve,means at the casting station for injecting liquid metal under pressureinto an injection passage communicating with the casting recess in oneof said molds to cause the metal to flow into said recesses andconnecting apertures to form with the stack of sheets an assembledrotor, means for withdrawing the molds out of engagement with thesleeves after the injecting operation, the carrier member then beingagain rotated to carry the sleeve with the assembled rotor to said feedand delivery station and at the same time carry a sleeve containing afurther stack of sheets to the casting station where the injectingoperation is repeated, and means for discharging the assembled rotorfrom the sleeve at the feed and delivery station for conveyance to areceiving station.

By this arrangement the casting of short-circuiting bars and rings in asquirrel cage rotor is greatly facilitated, notably because of theabsence of manual steps.

Indeed, the sleeves on the one hand and the dies on the other hand incombination constituting a mold, can be very easily replaced accordingto the requirements of the moment, by elements having the same functionbut of different dimensions and shapes.

In the case where such changes are made, it is clear that adjustmentsare necessary according to the operation to be carried out; thus anadjustment will be made at the feed station in order that the partsalways have their axes in alignment with the rods of the jacks to aid intheir transfer into the corresponding sleeve. The adjustment is rapidand precise and is obtained for example by means of wheels acting onscrews; it is thus possible if desired, to frequently change the castingmold with a minimum loss of time and good use of the machine; because ofthis, the machine of the invention enables parts in which the castingsand dimensions are substantially different to be made with a smallerquantity of equipment.

Other features and advantages of the invention will moreover appear fromthe following description given by way of example with reference to theaccompanying drawings, in which:

FIG. 1 illustrates in perspective a rotor for an electric motor havingbars and short-circuiting rings produced by the machine according to theinvention;

FIG. 2 shows a plan view of this machine;

FIG. 3 shows a corresponding elevation;

FIG. 4 shows a side view of he machine;

FIG. 5 shows the metal injection station in section along the line V-Yof FIG. 3;

FIG. 6 is a section along the line Y I V l of FIG. 5, the rotor stacksand the feed chute and delivery device not being shown;

FIG. 7 is a section along the line VII-VII of FIG. 2;

FIG. 8 is a view along the line VIIIVIII of FIG. 2; showing the feedstation;

FIG. 9 shows on a larger scale a sectional view along the line IX-IX ofFIG. 2;

FIG. 10 is a transverse section of the machine along the line XX of FIG.2;

FIGS. 11 to 17 show schematically one cycle of operation of operation ofthe machine;

FIGS. 18 to 24 are similar views of the operation of an alternativeembodiment.

Referring to FIG. 1, the rotor R, constituted in the usual manner by astack of magnetic metal sheets 5, has a central bore 6 for a temporaryspindle or axle 7. The sheets, perforated at 8, are stacked in such amanner as to constitute passages or tunnels which, when filled withmolten metal, constitute bars shown diagrammatically at B connectedtogether on the lateral faces of the rotor by circular short circuitingrings 9 and 10 which may possibly have cooling fins.

In the embodiment selected and shown in FIGS. 2 to 4, the machine formaking rotors for electric motors or other similar articles has a baseframe indicated generally at 12 of generally parallelepipedic form.

On its upper surface which forms a table 13, this frame has two fixedsupports 14 and 15 joined together by spacing bars, of which three areshown at 16, 16a, 16b. Between the fixed supports, the aforesaid barscarry a movable plate 17 coupled to a fixed hydraulic jack 18 whilst,between this movable plate and the fixed support 14, the bar 16b carriesand forms a rotational journal for a revolving sleeve-carrying plate 19,having two diametrically opposed bores 20, 21 (FIG. 5) each having asleeve 22, 23 for carrying a rotor stack.

A block 25 which receives a die 26 is fixed by screws 24 to the fixedsupport 14. This die has, facing the revolving plate 19, a central holeadapted to house one end ofthe temporary spindle 7, and a circulargroove 27 adapted to communicate by one or more channels 28 with aninlet cylinder 29 having an injection orifice E. A piston 30 movable inthe injection cylinder 29 constitutes the end part of a hydraulicinjection jack indicated by VI.

At the other side of the plate 19 and in the same axis, the movableplate 17 has a block 31 arranged to carry a second die 32 substantiallysimilar to the aforesaid one, i.e. having a central blind hole 33 forthe head of the temporary spindle and a circular groove 34.

By this arrangement, there is obtained at the injection station acasting device formed from three parts which are respectively a sleeve22 or 23 which receives the stacks of sheet metal, a first fixed die 26located at the injection side, and second die 32 which is movable underthe action of the jack l8 fixed rigidly to the frame and is adapted toensure the closing of the mold.

It will be noted that one arrangement of the machine enables severalarticles to be processed during a cycle. In this case the above mold isprovided with, for example, two sets of dies and two correspondingsleeves. It will be understood that for removing the finished rotors andplacing in position new stacks of sheets, the opposing jacks will beappropriately arranged.

The sleeve-carrying plate 19 is, on the one hand, reciprocally movablein a direction parallel to the bars 16, 16a and 16b and is adapted onthe other hand for alternate rotational swings through 180. Theseoperations are obtained by means of the arrangements which will now bedescribed.

Reference will be made for this purpose more particularly to FIGS. and 6in which it will be seen that the sleeve-carrying plate 19 is providedaxially, for the purpose of driving it in rotation, on its face remotefrom the injection, with a sleeve 38 at the end of which is fixed in anysuitable manner a pinion 39 adapted to cooperate with a vertical rack 40controlled by a jack 41.

Clearly, the rotation of he sleeve-carrying plate could be obtained in adifferent manner with the aid of reduction gearing or a hydraulic motor.

The sleeve-carrying plate 19 can thus be rotated in either direction ofrotation; it is moreover axially displaceable as indicated by the arrowF in FIGS. 2 and 5. For this purpose, the plate is mounted on ballbearings 42 and connected to a jack 43 carried by the fixed plate 14through a sliding assembly shown generally at 44. This assemblycomprises a T-shaped component 45 of which the ends of the horizontalportion 46 are immovably held between abutment faces 47 housed in acylindrical extension 48 of the injection sideplate 19. This portion ismovable in a hole 49 fonned in the bar 16b, while the other portion 50of the T is connected by a pin 51 to the rod 52 of a piston 53 of theaforesaid jack 43.

The block 31 carrying the die 32 has, adjacent to its outer edge athreaded hole 54 adapted to receive a stay rod 55 and a counter nut 56.At its free end, this rod had a head 57 adapted to cooperate with ahousing 59 formed in the plate 19; it will be noted that this rod isaxially adjustable and can enter a hole 60 provided in the movable plate17.

Diametrically opposed to this injection station described above, theplate 19 (FIG. 2) holds the other sleeve 22 as shown in the axis of afirst jack 61 located at the injection side of the plate, and of acoaxial second opposing jack 62, the first jack having a rod 63 (FIG. 7)while the rod 64 of the second jack is hollow and operable in eitherdirection along its axis.

These two jacks will now be described in greater detail. As will be seenfrom FIG. 7, the jack 6] is provided, at the end portion of its rod 63,with a removable rod extension 65, the diameter D of which is slightlyless than the diameter of the bore 6 formed in the rotor.

As regards the jack 62, it is adapted to actuate a retractable stopdevice which essentially comprises a lever 66 rockably mounted at 67 ona yoke, itself fixed on one of the fixing stocks 69 of the jack 62. Thelever 66 extends parallel to the jack 62 and has, at one end locatednear the sleeve-carrying plate 19, an extension 70 acting as a stopdirected towards the table 13 of the frame. At its other end situatedbeyond the pivot point of the lever 67, the lever 66 is subjected to theaction of a spring 72 connected to the table 13. Adjacent this end, thelever 66 is provided with a roller 76 rotatable on a shaft 77 whichroller is adapted to cooperate with the end portion of the hollow rod 64of the jack 62.

In order to prevent excessive movement of the lever 66, a limiter isprovided in the form of a bridge 78 associated with the end stock 69.

A channel 80 for the reception of assembled rotors R leads to a locationbetween the sleeve carrying plate 19 and the far end of the jack 62,which rotors are directed by means of the inclined chute 81 towards anappropriate receptacle (not shown), while an inclined channel 82, formedin the table, substantially beneath the yoke 68, is adapted to receiveand direct the temporary spindle 7 towards a receiving location eachmounted on temporary spindles as shown in FIG. 10.

In order to supply stacks of sheet metal each mounted on temporaryspindles the machine is provided with a supply station A (FIGS. 2 and4). This station, visible in greater detail particularly in FIGS. 8 and9, comprises in a feed shoot 85 a device 86 arranged to deliver stacksof sheets one by one onto a reception assembly indicated generally at Bcomprising two elements respectively 87 and 88.

The first element 87 is fixed to a bedplate 89 and the second is movableas shown by the arrow F2 in a direction which is transverse with respectto the frame. The elements 87, 88 have opposed inclined surfaces 90, 91downwardly converging and which thus form a reception V. The element 88has a threaded hole 92 for receiving a screw 93 rotatable by means of 5wheel 94 carried by a bearing 95 itself fixed to the bedplate 89. Thisbedplate 89 is slidably mounted by means of a slide on an intermediateelement 96 connected to a plate 97 which is itself movable in adirection perpendicular to the aforesaid direction by means of slideways98 fixed to the frame. Transverse movement of the bedplate 89 and of theassembly B is effected by a jack 100 which is coupled to a lug 101 ofthe bedplate, this jack being rigidly connected to the movable plate 97.For the control of its movement, the plate 97 has a threaded sleeve 102in which is engaged a screw 103 operable by a wheel 104 rotating in abearing 105 fixed laterally to the frame of the machine.

By virtue of such an arrangement, whatever may be the dimensions of thestacks of sheets R and of the sleeves, both in diameter and in length,these sheets can be conveniently presented into the axis 106 of thesleeve presented by the sleeve-carrying Thus, as will be seen from FIG.8.

In effect, it will be understood that the temporary spindle 6 of theserotors must be presented in the alignment of the rods 63 and 64respectively of the pistons 61 and 62, the common axis of whichcorresponds to the position indicated at 106. Thus, it is possible, bysimple operation of the wheel 94, to alter the spacing of the inclinedfaces 90 and 91 according to the diameters of the rotors R, in such amanner that the axis of the latter has the same length as that of theaforesaid axis 106, whereas manipulation of he wheel 104 enables thelongitudinal positioning of the rotors to be altered according to theirlength to adapt the device to rotors of various lengths. The jack 100 isadapted to position the stacks of sheets along the aforesaid axis.

The operation of the machine can be as shown diagrammatically in FIGS.11 to 17.

It will be assumed that the machine is in operation, a rotor R comingfrom the casting station M being ready to be extracted from the sleeve22 of the plate 19, and a stack of sheets R1 having been placed in thesleeve 23 and brought between the two dies 26 and 32; the plate 19 hasbeen moved away from the assembly constituted by the fixed plate 14 anddie 26 and the die 32 is itself spaced from the sleeve 23. The injectionpiston 30 is in a rearward position with respect to the plate 19 as wellas the pistons and rods 63 and 64 of the jacks 61 and 62, while the stopdevice 70 operated by the jacks is in an inoperative position by virtueof the position of the rod 64.

In a first step shown in FIG. 12, the jack 43 is fed and its piston 55(see FIG. 13), moving in the direction of the arrow F3, drives therevolving plate 19 against the fixed due 26, following which the jack 18is pressurized and this drives the movable die 32 firmly into contactwith the corresponding face of the sleeve 23.

By this arrangement, the lateral faces of the stack of sheets R1 closeon the circular grooves 27 and 34 themselves in communication by meansof the tunnels formed by the perforations 8 aligned, for example,helically, the die 26 being in communication by the channel 28 with theinjection chamber 29.

During this time, the jacks 61 and 62 have been placed under pressureand the forward ends of the rod 64 and 63 have come into contact withthe corresponding lateral faces of the assembled rotor R. It will benoted that the rod 64 is provided to come into contact with the lateralface of the rotor, while the rod extension portion 65 of the rod 63, bypenetrating into the bore 6 of the rotor pushes back the temporaryspindle 7 into the tubular rod 64, the temporary spindles previouslyremoved being also pushed back ensuring the ejection of the last ofthese into the channel 82.

In this position the assembled rotor R is nipped between the jacks 61and 62; the cast short-circuiting rings 10 and 11 and the bars 8 arevisible together with the sprue C, while at the casting station M,molten metal is introduced into the injection cylinder 29 through theorifice E.

For a better understanding, phases of operation will now be describedseparately although they are carried out simultaneously.

In FIG. 13, liquid metal is injected into the rotor by operating theinjection jack Vl, the piston 30 of which ensures the introduction ofmolten metal under pressure into the aforesaid circular grooves andtunnels 27, 34 and 8 to form the connecting bars B and rings 9 and 10.

The jack 61 has a thrust greater than that of the jack 62, and thisbeing so, it pushes back the rod 64 of the latter at the same timecarrying with it the rotor R which is still nipped between the two rods;it is thus first extracted from fixed sleeve 22 and then droppedstraight down into the discharge channel 80. It should be noted that thethrust of the jack 61 has, during the extraction of the rotor R from thechuck, caused the rupture of the sprue C which is shown still attachedto the plate 19; moreover, the stop device 70 has been brought by thetubular rod 64 into its operative position between the sleeve 22 and therear face of the rotor R being ejected, in order to prevent rearwardmovement of the rotor R' when the rod 63 of the jack 61 is movedrearwardly as is shown in FIG. 14.

In this figure, the jack 62 is still in its rearward position, while thejack 61 is with respect to the previous phase itself brought back to itsstarting position, so that the freed rotor R falls into the channel 80,where it slides under gravity towards a receptacle (not shown).

In FIG. 15, the feed station A has delivered a stack of sheets R2 sothat the latter is located first in the reception V and then alignedwith the axis 106 of the opposed jacks 61 and 62, as will be seen fromFIG. 16, the jack 62 is again pressurized and its rod 64 pushes thestack of sheets R2 into the sleeve 22, the sprue C, if still there,being then removed from the plate 19.

In a final phase of the cycle, shown in FIG. 17, the metal in the rotorR, R is sufficiently cooled for the rotor to be removed from the die.The piston 30 is retracted to its initial position, and then the jack I8is actuated so that it too returns to its initial position. Thesleeve-carrying plate 19, being thus freed, can be brought by the jack43 into an intermediate position between the two dies 26, 32. Duringthis movement of the plate, the pinion 39 (FIGS. 5 and 6) comes intomesh with the teeth 40 of the rack and the latter is operated to causethe plate 19 to rotate half a turn so that the assembled rotor R'l isbrought into the place of the stack of sheets R2 which itself is broughtto the cast assembly and the new cycle commences.

Such a machine enables the manufacture of rotors of various types. Aseries of rotors of a certain type having been completed, rotors ofanother type can be rapidly casted by changing the dies and the sleevesin that their mounting and dismounting on their respective supports iseasily effected.

When the parts to be worked are changed, it is clear that it isnecessary to adjust the supply station in order that the new parts shallbe conveniently placed for transfer and loading into the waiting sleeve.

In all cases, such a machine avoids time wastage due principally tohandling, enables parts of very different sizes to be cast by adaptationof the casting molds, eliminates the considerable tooling necessaryhitherto and finally permits a feed head to be formed on the rotorsresulting in a more consistent metal casting which leads to an increasedelectrical efficiency.

Jacks ensuring the extraction of the rotor from the chuck and thetransfer of a stack of sheets into the latter from the supply station Afor casting, could carry out these operations as shown in FIGS. 18 to24.

In these Figures, the same references have been used to designatesimilar elements; the sleeve-carrying plate 19 is the same as before, asare the casting and supply stations M and A respectively. The jack 62 isreplaced by a jack having a simple tubular rod 111 adapted to receivethe temporary spindles 112 which, in the case considered, are headless;the rod 111 has a longitudinal opening 113, the purpose of which willappear from the following. As regards the other opposing jack 114, itcomprises a rod 115 and a rod extension 116 adjacent to which arelocated stop elements 117 and a stop means similar to that describedpreviously but which is, in this case,

disposed on the other side of the fixed plate carrying the die 26.

The operation of the embodiment of FIGS. 18-24 is substantially thatdescribed with respect to FIGS. 11-17. However, it will be seen (FIG.19) that the two jacks are pressurized together while the mold is closedand molten metal is being poured into the injection chamber.

In FIG. 20, the jack 110, continuing its movement, extracts the rotor R5from the sleeve 22 and engages it on the rod extension 116. This causes,on the one hand, breakage of the sprue C by means of the stops 117 and,on the other hand, the automatic ejection of the temporary spindle 112;during this time, injection of metal into the stack of plates R6 iseffected at the molding station.

In a subsequent phase (FIG. 21) the two jacks 110 and 114 are returnedto their original positions; the rotor R5, being no longer held, fallsinto the channel 80 and moves under gravity towards a receptacle.

In another phase (FIG. 22) the supply station A has freed a stack ofsheets R7 whose temporary spindle is, as before, located in alignmentwith the rods of the jacks.

In the following phase (FIG. 23), the jack I10, placed under pressure,ensures the transfer of the stack of sheets R7 into the sleeve 22;during this time, the metal injected into the rotor at the moldingstation, cools while maintained under pressure.

In a final phase of the cycle (FIG 24), the plate 19, disengaged fromthe fixed and movable dies, respectively 26 and 32, is swung in a rotarymovement through by the rack 40 meshing with the pinion 39 ashereinabove described, so that the finished rotor R'6 is brought intothe place of the stack R7 and vice versa.

I claim:

1. A machine for casting under pressure rotors for electric rotors froma stack of magnetic sheets having apertures, said machine comprising arotatable carrier member having at least two bores for receiving sleevessupporting stacks of sheets, a feed and delivery station including apair of opposed jacks disposed on opposite sides of the carrier member,the first of said jacks loading a stack of sheets in a said bore in thecarrier member, the second of said jacks cooperating with the first jackfor removing an assembled rotor from a said bore, and a casting stationcomprising a pair of opposed dies and injection casting means forflowing molten metal into the stack of metal sheets, and means forrotating the carrier member so that one of said bores is first inposition relative to the feed station for loading a stack of sheets intoa said bore, then in position relative to the casting station forinjecting molten metal therein and then in position relative to thefeeding and delivery station for unloading the assembled rotor from thebore.

2. A machine as claimed in claim 1, wherein a second of said bores isarranged in the carrier member so that when the first of said bores isin said position relative to the feed and delivery station, said secondbore is in said position relative to the casting station and vice versa.

3. A machine as claimed in claim 1, wherein a temporary spindle extendsthrough the aperture in the stack of metal sheets, and wherein saidsecond jack has means for removing the temporary spindle during theunloading of the assembled rotor.

4. A machine as claimed in claim 3, wherein said first jack has a hollowtubular rod receiving the temporary spindles removed from the assembledrotor during the withdrawal thereof.

5. A machine as claimed in claim 1, wherein the carrier member has afirst axial position at which the feeding, discharging and injectionoperations take place and second axial position at which rotation of thecarrier member takes place, and means for displacing the carrier memberfrom the first to the second position and vice versa.

6. A machine as claimed in claim 1, wherein the carrier member has anaxial sleeve for rotatably mounting and axially displacing, the sleevebeing coupled to a control jack and having a pinion cooperating with arack.

7. A machine as claimed in claim 6, wherein the coupling of the carriermember to the control jack comprises a T-shaped member whose stem issecured to the end of the piston rod of the said control jack and whosecross limb is associated with the carrier member between two ball races,the cross limb being longitudinally movable in an opening in a supportfor the carrier member.

8. A machine as claimed in claim 1, further comprising a feed hopper forthe stacks of sheets, said hopper feeding to a V-shaped feed channelformed in a feed member movable by an associated jack from a receivingposition below the mouth of the hopper to a feeding position with theaxis of the stack in axial alignment with the sleeve at the feed anddelivery station.

9. A machine as claimed in claim 8, wherein the V-shaped channel has oneside movable relative to the other side for varying the height of theaxis of the stack relative to the channel.

10. A machine as claimed in claim 8, wherein the V-shaped channel iscarried by a bedplate movable in a slideway parallel to the axis ofrotation of the carrier member.

11. A machine as claimed in claim 8, comprising a movable stop member atthe mouth of the hopper and means for intermittently actuating the stopmember to move the stop member into operative position synchronouslywith the operation of the machine.

12. A machine as claimed in claim 3, comprising a movable discharge stopmember operable by the discharge jack on the discharge side of thecarrier member from inoperative position where the stop member allowsunopposed discharging movement of the assembled rotor from said sleeve,to an operative position where the stop member prevents return movementof said discharged rotor into said sleeve upon retracting movements ofthe opposed jacks.

13. A machine as claimed in claim 4, wherein the hollow rod is formedwith a longitudinal opening through which the temporary spindles areejected.

1. A machine for casting under pressure rotors for electric rotors froma stack of magnetic sheets having apertures, said machine comprising arotatable carrier member having at least two bores for receiving sleevessupporting stacks of sheets, a feed and delivery station including apair of opposed jacks disposed on opposite sides of the carrier member,the first of said jacks loading a stack of sheets in a said bore in thecarrier member, the second of said jacks cooperating with the first jackfor removing an assembled rotor from a said bore, and a casting stationcomprising a pair of opposed dies and injection casting means forflowing molten metal into the stack of metal sheets, and means forrotating the carrier member so that one of said bores is first inposition relative to the feed station for loading a stack of sheets intoa said bore, then in position relative to the casting station forinjecting molten metal therein and then in position relative to thefeeding and delivery station for unloading the assembled rotor from thebore.
 2. A machine as claimed in claim 1, wherein a second of said boresis arranged in the carrier member so that when the first of said boresis in said position relative to the feed and delivery station, saidsecond bore is in said position relative to the casting station and viceversa.
 3. A machine as claimed in claim 1, wherein a temporary spindleextends through the aperture in the stack of metal sheets, and whereinsaid second jack has means for removing the temporary spindle during theunloading of the assembled rotor.
 4. A machine as claimed in claim 3,wherein said first jack has a hollow tubular rod receiving the temporaryspindles removed from the assembled rotor during the withdrawal thereof.5. A machine as claimed in claim 1, wherein the carrier member has afirst axial position at which the feeding, discharging and injectionoperations take place and second axial position at which rotation of thecarrier member takes place, and means for displacing the carrier memberfrom the first to the second position and vice versa.
 6. A machine asclaimed in claim 1, wherein the carrier member has an axial sleeve forrotatably mounting and axially displacing, the sleeve being coupled to acontrol jack and having a pinion cooperating with a rack.
 7. A machineas claimed in claim 6, wherein the coupling of the carrier member to thecontrol jack comprises a T-shaped member whose stem is secured to theend of the piston rod of the said control jack and whose cross limb isassociated with the carrier member between two ball races, the crosslimb being longitudinally movable in an opening In a support for thecarrier member.
 8. A machine as claimed in claim 1, further comprising afeed hopper for the stacks of sheets, said hopper feeding to a V-shapedfeed channel formed in a feed member movable by an associated jack froma receiving position below the mouth of the hopper to a feeding positionwith the axis of the stack in axial alignment with the sleeve at thefeed and delivery station.
 9. A machine as claimed in claim 8, whereinthe V-shaped channel has one side movable relative to the other side forvarying the height of the axis of the stack relative to the channel. 10.A machine as claimed in claim 8, wherein the V-shaped channel is carriedby a bedplate movable in a slideway parallel to the axis of rotation ofthe carrier member.
 11. A machine as claimed in claim 8, comprising amovable stop member at the mouth of the hopper and means forintermittently actuating the stop member to move the stop member intooperative position synchronously with the operation of the machine. 12.A machine as claimed in claim 3, comprising a movable discharge stopmember operable by the discharge jack on the discharge side of thecarrier member from inoperative position where the stop member allowsunopposed discharging movement of the assembled rotor from said sleeve,to an operative position where the stop member prevents return movementof said discharged rotor into said sleeve upon retracting movement ofthe opposed jacks.
 13. A machine as claimed in claim 4, wherein thehollow rod is formed with a longitudinal opening through which thetemporary spindles are ejected.